What frost giant built a boat to survive Ymir's blood flood?

What frost giant built a boat to survive Ymir’s blood flood? Bergelmir did. In the creation story preserved in Snorri Sturluson’s Prose Edda, the gods kill the primordial giant Ymir, and his immense blood flow drowns nearly all the frost giants.

Bergelmir escapes with his household aboard a lúðr, a difficult Old Norse term variously translated as a boat, vessel, chest, trough, or mill structure. Because of this vocabulary, the exact construction is debated, but the familiar “boat” answer accurately reflects a major translation tradition and the story’s ark-like imagery.

Bergelmir and his wife survive the catastrophe and become ancestors of later frost-giant generations. The episode resembles a primeval flood survival narrative, although Norse sources do not present it as a direct retelling of the biblical Noah story.

A common mix-up is confusing Bergelmir with Ymir. Ymir is the slain primordial giant whose blood causes the flood; Bergelmir is the survivor. In the Poetic Edda, the image is briefer and more cryptic, while the Prose Edda expands it into a clearer survival account.